The proposed research is designed to obtain detailed knowledge of gonadotropin receptor-adenylyl cyclase system of the subhuman primate (monkey) corpus luteum. The major objectives include: (a) characterization of the receptors for luteinizing hormone (LH) and chorionic gonadotropin (CG) and the LH/CG-sensitive adenylyl cyclase system in macaque luteal tissue; (b) examination of the relationship between gonadotropin receptor-adenylyl cyclase activity and the functional state of the corpus luteum during the nonfertile menstrual cycle; (c) investigation of the direct effects of estrogen and prostaglandins on gonadotropin receptors and adenylyl cyclase activity in luteal tissue in vitro; and, (d) administration of daily injections of increasing doses of chorionic gonadotropin to monkeys to mimic early pregnancy and to assess the effects on gonadotropin receptor-adenylyl cyclase activity in the corpus luteum. Unoccupied gonadotropin receptors of the macaque corpus luteum will be characterized from the specific interaction of 125I-labeled hLH and hCG with a particulate preparation of luteal tissue under controlled in vitro conditions. The number of receptors occupied by endogenous LH or administered hCG will be quantified indirectly via radioimmunoassay of gonadotropin eluted from luteal tissue. Adenylyl cyclase activity will be assessed from the conversion of (alpha 32P) ATP to (alpha 32P) cAMP by the particulate preparation of luteal tissue. The combined objectives are basic to our understanding of the role of the gonadotropin receptor-adenylyl cyclase system in the development, function and regression of the primate corpus luteum. Moreover, these studies would determine whether early pregnancy in the primate offers a physiologic model for the study of gonadotropin regulation of its own receptor-adenylyl cyclases system. The proposed investigation should provide new information on the cellular mechanisms regulating the menstrual cycle and early pregnancy in primates, with application to the human condition.